Field of the Invention
This invention relates generally to blow molded containers. In particular, this invention relates to mold assemblies wherein the so-called “neck finish” (surface feature for engaging a container closure) is formed in the blow molding process.
Description of Related Art
Blow molding is a cyclic process wherein a hollow tubular preform of material in a moldable condition is centered on the parting plane of a mold assembly, the mold assembly is closed around the preform, the preform is expanded so the exterior of the preform abuts molding surfaces defined by the closed mold assembly, the blow molded article is conditioned to be sufficiently rigid to retain its size and shape while unsupported, the mold assembly is opened and the blow molded article is removed. In general, the moldable condition of the preform is achieved when the material of the preform is at an elevated temperature, and the rigid condition of the blow molded article is achieved when the temperature of the material has been reduced. A blow molding machine comprises a press for opening and closing the mold assembly and pressurizing apparatus for introducing a pressurized fluid (typically air) to expand the preform in the closed mold assembly. One type of blow molding equipment produces blow molded containers from tubular extrusions produced by extruding equipment arranged relative a molding assembly to position one or more extrusions in the parting plane of the mold assembly. A substantially tubular extrusion extends below the lower end of a cavity defined by mating mold members and, with abutment of the mating mold members, the lower extremity of the extrusion is closed leaving the upper end of the extrusion open so as to create a blow moldable preform.
Blow molding is commonly used for production of containers for transporting, storing and dispensing liquids wherein the blow molded article comprises a body portion and a neck connecting the container body with a mouth opening for filling the container and dispensing the contents therefrom. Advantageously, the neck portion of the container comprises an exterior surface having one or more features, referred to herein as the “neck finish”, for engaging a separable closure for covering the mouth opening. Known neck finish features include: (i) screw type threads for engaging mating threads on a shank of a closure; and, (ii) at least one protruding circumferential ring, such as a so-called “snap ring” for engaging compatible features in a shank of a closure to resist detachment of the closure from the neck finish. Mold assemblies for blow molding containers comprise mating mold components wherein molding surfaces open to the mating faces of the mold components define the exterior of the container. Advantageously, mold assemblies comprise replaceable insert components for forming the neck portion, wherein the neck insert mold components define the exterior surface of at least the neck finish. Use of replaceable neck insert mold components facilitates production of containers that differ only in the neck finish as well as replacement of inserts that become worn or otherwise degraded through use.
Known constructions of mold assemblies with replaceable neck insert mold components retain those insert components in the mold assemblies with fasteners that require use of tools for removal and installation of the neck insert mold components. Consequently, the time required to replace neck insert mold components is impacted by the time required to remove and install fasteners retaining a neck insert mold component. Under circumstances where container production is interrupted solely for changing from containers accepting one closure type to containers accepting a different closure type, time for replacement of neck finish inserts is a component of lost production time. Hence, there is a need to provide neck insert mold components and retaining devices therefore that reduce the time required for neck insert mold component replacement in mold assemblies.